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Thrust vectoring control of vertical/short takeoff and landing aircraft

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Science China(Information Sciences) 2020年第2期63卷 218-220页

作者： Xiangyang WANG Bin zhu jihong zhu Zhiqiang CHENG Department of Computer Science and Technology Tsinghua University Automation Academy Nanjing University of Science and Technology

Thrust-vectored vertical and/or short take-off and landing (V/STOL) aircraft use a vertical lift fan and a 3-bearing swivel duct (3BSD) nozzle to deliver vertical takeoff, landing and short takeoff capability. The ban... 详细信息

关键词： BSD Thrust vectoring control of vertical/short takeoff and landing aircraft

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肺炎克雷伯菌肝脓肿侵袭综合征临床特点分析

中华急诊医学杂志 2024年第4期33卷 485-489页

作者：马勇孙东月杜昌高伟波朱继红迟骋北京大学人民医院急诊科北京100044

目的为分析肺炎克雷伯菌肝脓肿侵袭综合征(invasive klebsiella pneumoniae liver abscess syndrome,IKPLAS)临床特征,并与普通细菌性肝脓肿(common pyogenic liverabscess,CPLA)进行对比。方法收集北京大学人民医院2011年1月至2021年12月期间因细菌性肝脓肿住院患者的社会人口学及临床资料。根据是否合并侵袭性感染及细菌病原学结果筛选出肺炎克雷伯菌肝脓肿侵袭综合征,与普通细菌性肝脓肿进行对比,比较两组患者的一般资料、症状、既往病史、辅助检查、预后情况等指标。结果纳人172例细菌性肝脓肿患者,其中25例肺炎克雷伯菌肝脓肿侵袭综合征。相对CPLA组,IKPLAS组发热比例更低,糖尿病病史比例更高,单核细胞比例更低,降钙素原、尿素氮更高(均P0.05)。IKPLAS组最常见的侵袭感染部位为肺(22/25),脑(9/25),眼(9/25)。结论IKPLAS相对CPLA临床特点有所差异,最常见的侵袭感染部位为肺,脑,眼。本研究中二者病死率差异无统计学意义。对于病原学为肺炎克雷伯菌的细菌性肝脓肿,需要仔细评估是否存在侵袭病灶并予以针对性局部治疗,以更好地改善患者预后。

关键词：肺炎克雷伯菌肝脓肿侵袭综合征高毒力肺炎克雷伯菌侵袭病灶眼内炎预后病死率

急性肺栓塞合并血小板减少患者临床特点的回顾性研究

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中国全科医学 2024年第27期27卷 3372-3377页

作者：王武超刘思齐刘倩倩朱继红北京大学人民医院急诊科北京市100044

背景急性肺栓塞(APE)是严重的心血管疾病,近年APE合并血小板减少患者的检出率不断增加,存在血栓和出血的双重问题,目前研究主要以成功的病例报道为主,存在一定的临床评估和治疗方案的研究缺口。目的探讨APE合并血小板减少患者的临床特... 详细信息

背景急性肺栓塞(APE)是严重的心血管疾病,近年APE合并血小板减少患者的检出率不断增加,存在血栓和出血的双重问题,目前研究主要以成功的病例报道为主,存在一定的临床评估和治疗方案的研究缺口。目的探讨APE合并血小板减少患者的临床特征和临床预后,为临床提供诊疗依据。方法回顾性纳入2015年1月—2020年1月北京大学人民医院急诊科就诊的APE合并血小板减少患者21例为研究对象。将患者按照出血情况分为严重出血组(7例)和轻微/无出血组(14例);依据患者是否合并除肺动脉以外其他部位血栓将患者分为多部位血栓组(7例)和肺动脉血栓组(14例);依据患者死亡情况将患者分为死亡组(5例)和存活组(16例)。收集患者临床资料并进行组间比较。结果本研究共纳入APE合并血小板减少患者21例,其中男7例,女14例,平均年龄(63.2±18.9)岁。分析病因,免疫性血小板减少性紫癜5例,抗磷脂抗体综合征4例,嗜酸性粒细胞增多症3例,药物相关血小板减少2例,系统性红斑狼疮2例,肿瘤相关性血小板减少2例,病因不明3例。19例患者进行抗凝治疗。肺动脉血栓组纤维蛋白原、纤维蛋白原/白蛋白比值高于多部位血栓组(P<0.05)。严重出血组男性比例、平均血小板体积低于轻微/无出血组,多部位血栓比例、中心粒细胞/淋巴细胞比值高于轻微/无出血组(P<0.05)。死亡组抗凝治疗比例、血小板计数低于生存组,心率、平均血小板体积/血小板比值、肿瘤相关血小板减少比例高于生存组(P<0.05)。结论APE合并血小板减少患者存在多血栓事件风险,抗凝治疗有助于改善临床预后,依据血小板计数开展抗凝治疗与严重出血事件无相关性,血小板计数、血小板相关参数及其他凝血相关参数有助于血栓负荷、出血风险及临床预后的评估。

关键词：肺栓塞血小板减少预后回顾性研究

Design of nanofluid-cooled heat sink using topology optimization

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Chinese Journal of Aeronautics 2021年第2期34卷 301-317页

作者： Bin ZHANG jihong zhu Gaoxiang XIANG Limin GAO Deparment of Engineering Mechanics School of MechanicsCivil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'an 710072China MIIT Lab of Metal Addive Manufacturing and Innovative Design Northwvestern Polytechrical UniversilyXi'an 710072China School of Power and Energy Northwestern Polytechnical UniversityXi'an 710072China

The paper presented topology optimization of 2 D and 3 D Nanofluid-Cooled Heat Sink(NCHS). The flow and heat transfer problem in the NCHS was treated as a single-phase nanofluid based convective heat transfer model. The temperature-dependent fluid properties were taken into account in the model due to the strong temperature-dependent features of nanofluids. An average temperature minimum problem was studied subject to the fluid area and energy dissipation constraints by using the density method. In the method, the design variable is updated according to the gradient information obtained by an adjoint based sensitivity analysis process. The effects of the energy dissipation constraint, temperature-dependent fluid properties and nanofluid characteristics on optimal configurations of NCHS were numerically investigated with following ***, branched flow channels in the optimal configuration increased with the rise of the allowed energy dissipation. Secondly, temperature-dependent fluid properties were significant for obtaining the appropriate optimal results with best cooling performance. Thirdly, heat transfer performances of optimal configurations were enhanced by reducing the nanoparticle diameter or increasing the nanoparticle volume fraction. Fourthly, the optimal configuration for nanofluid had better cooling performance than that for its base fluid.

关键词： Forced convection Heat sinks Heat transfer Nanofluid Sensitivity analysis Topology optimization

基于机器学习的变刚度纤维增强复合材料最小化结构柔顺性优化设计

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力学学报 2024年第7期56卷 1849-1860页

作者：段尊义刘亿张皓翔陈志远徐斌朱继宏阎军西北工业大学力学与土木建筑学院西安710072 西北工业大学深圳研究院广东深圳518063 西北工业大学机电学院西安710072 大连理工大学工业装备结构分析优化与CAE软件全国重点实验室辽宁大连116024

纤维增强复合材料层合板的变刚度优化设计,通过逐点优化纤维铺角的可设计性,从而匹配结构中应力状态的空间变化,更高效地发挥纤维增强复合材料层合板在强度与刚度性能上的方向性,为设计师提供了更广阔的设计空间与设计灵活度.然而,基于... 详细信息

纤维增强复合材料层合板的变刚度优化设计,通过逐点优化纤维铺角的可设计性,从而匹配结构中应力状态的空间变化,更高效地发挥纤维增强复合材料层合板在强度与刚度性能上的方向性,为设计师提供了更广阔的设计空间与设计灵活度.然而,基于梯度类算法的传统复合材料变刚度优化设计,因其设计变量众多,不可避免地在结构分析与灵敏度分析中面临大规模计算的挑战.同时,结构在概念设计阶段存在载荷工况随机性问题,如何在初始概念设计阶段,针对随机载荷工况制定高效的设计方案具有重要工程价值.近年来,随着人工智能与高性能计算的快速发展,基于传统优化获得的数据集构建端到端的机器学习模型,为实现实时的复合材料变刚度优化提供了可能.文章采用反向传播(back propagation,BP)神经网络算法,建立了基于机器学习的纤维增强复合材料变刚度优化设计方法.首先,基于正态分布纤维优化(normal distribution fiber optimization,NDFO)插值格式,构建以最小化结构柔顺度为目标的复合材料变刚度优化设计模型,考虑载荷大小与方向的随机性,获得神经网络模型训练所需的样本集数据.其次,以最小均方误差(means square error,MSE)为目标函数,采用BP神经网络模型对样本数据集进行训练.最后,建立基于皮尔逊相关系数(Pearson correlation coefficient)、均方误差的模型评价体系,对生成的神经网络模型进行评价.数值算例讨论了含圆孔MBB梁与悬臂C型梁变刚度优化设计,详细阐述了基于机器学习的复合材料变刚度优化方法的实施过程,系统地对比了所提出的基于机器学习的复合材料变刚度优化与传统基于NDFO插值格式复合材料变刚度优化设计结果在纤维铺角轨迹和目标函数的差异,验证了本方法的有效性.

关键词：变刚度优化设计机器学习反向传播神经网络正态分布纤维优化纤维铺角

Optimization design of chiral hexagonal honeycombs with prescribed elastic properties under large deformation

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Chinese Journal of Aeronautics 2020年第3期33卷 902-909页

作者： Kepeng QIU Ruoyao WANG jihong zhu Weihong ZHANG School of Mechanical Engineering Northwestern Polytechnical UniversityXi’an 710072China

Flexible chiral honeycomb cores generally exhibit nonlinear elastic properties due to large geometric *** effective elastic moduli and Poisson's ratio typically vary with an increase in ***,the size and shape optimization of the chiral hexagonal honeycombs was performed to keep the Young's moduli and Poisson's ratio unchanged under large *** size of the honeycomb unit cell and the position coordinates of the key points were defined simultaneously as design *** equivalent Young's modulus and Poisson's ratio of chiral honeycombs were calculated through geometric nonlinear *** objective was to minimize the allowable tolerance between the prescribed and actual properties within the range of the target strain.A genetic algorithm was then *** optimal results demonstrate that the chiral honeycombs can maintain effective elastic properties that do not vary under large *** results are meaningful to morphing aircraft designs.

关键词： Chiral hexagonal honeycombs Genetic algorithm Geometric nonlinearity Large deformation Shape optimization

Precise output loads control of load-diffusion components with topology optimization

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Chinese Journal of Aeronautics 2020年第3期33卷 933-946页

作者： Yinfeng CAO Xiaojun GU jihong zhu Weihong ZHANG State IJR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical UniversityXi’an 710072China Institute of Intelligence Material and Structure Unmanned System TechnologiesNorthwestern Polytechnical UniversityXi’an 710072China MIIT Lab of Metal Additive Manufacturing and Innovative Design Northwestern Polytechnical UniversityXi’an 710072China

The purpose of this paper is to present a novel topology optimization approach to control precisely the output loads under static loads and harmonic *** introduce the Artificial Bar Element(ABE)at the designated output positions,where the output loads are equivalently measured and constrained with the nodal displacements of *** model is then formulated considering the output load constraints as well as the minimization of strain energy and dynamic displacement responses respectively under the static and dynamic *** influences of the ABEs stiffness,different material usages of the design domain,widths of the output loads constraint intervals and variation ratios of output loads are discussed in *** proposed method is verified with several numerical examples with clear and reasonable load transfer paths.

关键词： Artificial bar elements Dynamic response Kreisselmeier-Steinhauser(KS)function Precise control of output loads Topology optimization

Multiscale topology optimization using feature-driven method

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Chinese Journal of Aeronautics 2020年第2期33卷 621-633页

作者： Zhao XU Weihong ZHANG Ying ZHOU jihong zhu State IJR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical UniversityXi’an 710072China

This paper presents a multiscale design method for simultaneous topology optimization of both macrostructures and *** features are extended as design primitives at both macro and micro scales and represented by Level Set Functions(LSFs).Parameters related to the locations,sizes,and orientations of macro and micro features are considered as design variables and optimized *** the overlapping areas of different macro features,embedded microstructures are optimally figured out as the solution of the corresponding sub-optimization,*** this study,the eXtended Finite Element Method(XFEM)is implemented for structural and sensitivity analyses with respect to design *** method has the advantage of using a fixed grid independent of the topology optimization *** homogenization procedure is applied to calculate the effective properties of considered microstructures in each macro *** examples are presented to illustrate the effectiveness of the proposed *** depict that the multiscale design cannot obviously improve structural stiffness compared with a solid-material design under the linear elastic condition.

关键词： Feature-driven method Level set function Multiscale design Topology optimization XFEM

Structural topology optimization under stationary random base acceleration excitations

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Chinese Journal of Aeronautics 2019年第6期32卷 1416-1427页

作者： Fei HE Hongqiang LIAO jihong zhu Zhongze GUO Institute of Systems Engineering China Academy of Engineering PhysicsMianyang 621900China State IJR Center of Aerospace Design and Additive Manufacturing Northwestern Polytechnical UniversityXi’an 710072China

Structural topology optimization subjected to stationary random base acceleration excitations is investigated in this paper. In the random response analysis, the Large Mass Method(LMM) which attributes artificial large mass values at each driven nodal Degree Of Freedom(DOF) to transforming the base acceleration excitations into force excitations is proposed. The Complete Quadratic Combination(CQC) which is commonly used to calculate the random responses in previous optimization has been proven to be computationally expensive especially for large-scale problems. In order to conquer this difficulty, the Pseudo Excitation Method(PEM) and the combined method of PEM and Mode Acceleration Method(MAM) are adopted into the dynamic topology optimization, and random responses are calculated using these two methods to ascertain a high efficiency over the CQC. A density-based topology optimization method minimizing dynamic responses is then formulated based on the integration of LMM and PEM or the combined method of PEM and MAM. Numerical examples are presented to verify the accuracy of the proposed schemes in dynamic response analysis and the quality of the optimized design in improving dynamic performance.

关键词： Dynamic response Large mass method Mode acceleration method Pseudo excitation method Random base acceleration excitations Topology optimization